(a) Field of the Invention
The present invention relates to a thin film transistor array panel and a manufacturing method thereof.
(b) Description of Related Art
Liquid crystal displays (LCDs) are among the most widely used flat panel displays. An LCD includes two panels provided with field-generating electrodes, such as pixel electrodes and a common electrode, and a liquid crystal (LC) layer interposed therebetween. The LCD displays an image by applying voltages to the field-generating electrodes to generate an electric field in the LC layer, which controls an orientation of LC molecules in the LC layer to adjust polarization of incident light.
Among the different types of LCDs, a vertical alignment (VA) mode LCD achieves a high contrast ratio and wide reference-viewing angle. The VA mode LCD aligns (e.g., tilts) LC molecules such that the long axes of the LC molecules are perpendicular to the panels in the absence of an electric field.
The reference-viewing angle of the VA mode LCD depends upon the arrangement of cutouts in the field-generating electrodes and protrusions on the field-generating electrodes. The cutouts and the protrusions can determine the tilt of the LC molecules. The reference-viewing angle can be widened by appropriately arranging cutouts and protrusions to vary the tilt of the LC molecules.
In the VA mode LCD, poor lateral visibility can be a problem. The pixel electrodes of the VA mode LCD overlap signal lines for transmitting signals to the pixel electrodes for increasing the aperture ratio and a thick, low dielectric insulator is disposed between the pixel electrodes and the signal line for reducing parasitic capacitance between the pixel electrodes and the signal lines
The thick insulator causes deep contact holes for connecting the signal lines and the pixel electrodes, etc., and thus sidewall profiles of the contact holes need to be smoothed. The smooth sidewalls of the contact holes cause light leakage, thereby degrading image quality. Although the light leakage may be substantially blocked by widening opaque members in the LCD, widened opaque members may decrease the aperture ratio.
Therefore, a need exists for a thin film transistor array panel for improving the lateral visibility in LCDs.